Mechanism for safely controlling internal-combustion engines upon aircraft



Dec. 6, 1927.

'r. DOUGLAS MECHANISM FOR SAFELY CONTROLI 'JING INTERNAL COMBUSTION ENGINES UPON AIRCRAFT 27. 1917 s She ets-Sheet 1 Original Filed Dec Tia- INVENTOR. BY Theon'mvfimg l Q/Vmm T: DOUGLAS MECHANISM FOR SAFELY CONTROLLING INTERNAL COMBUSTION ENGINES UPON AIRCRAFT Original Filed Dec. 27. 1917 5 Sheets-Sheet 2 [N VE N TOR. MM W Dec. 6, 1927. 1,651,919

T. DOUGLAS MECHANISM F31. SAFELY CONTROLLING INTERNAL COMBUSTION ENGINES UPON AIRCRAFT Original Filed Dec. 27. 1917 3 Sheets-Sheet 5 21 I 38 {z 27 22. I 19 +7 INVENTOR. MW

7. 1 a. ATTORNEY Patented pa. 6, 1927. r p

' UNITED [STATES 1 96 gi PATE OFFICE.

' THEODORE DOUGLAS, OF SCARBORO, NEW YORK, ASSIGNOR T DUPLEX ENGI NE GOV- ERROR COMPANY, INC., 0F BROOKLYN, NEW YORK, A CORPORATION 01 NEW YORK-' mscnanrsm ronsArELY comma-caninernrnrman-comnqsrron Enemies nron AIRCRAFT. 1

Application filed December 27, 1917, Serial No. 209,130. Renewed April 7, 1827.

er aircraft; and has for its primary object to provide an attachment which can be combined with the power system of which the engine is the principal part, in such a way that, in case of a mishap of any kind resulting in a great shock to the engine, the operation of the latter is interrupted at once; this cessation of the running of the engine being preferably brought about by.the automatic.

suspending of the operation of the ignition system by which electrical current is supplied to the cylinders 'ofthe engine to produce combustion of the explosive charges therein.

A further object of my invention is to pro-- vide an attachment which will be simple in construction and capable of being easily applied and connected in operative relation to an aeroplane engine for example, so that it will instantly and infallibly cause the engine to stop, whenever an accident of any sort takes place which is apt to produce serious measures by hand to insure his own safety and the safety of his machine.

It very often happens when an aviator is making a flight that a propeller blade breaks 40 or something else happens; with the result that the'engine immediately becomes so unbalanced as to wrench itself loose from its anchorage before it can be stopped. Frequently in such cases the gasoline line is broken and fire has been known to start as a consequence of the continued sparking in the enginecylinders and the flaming exhaust into the atmosphere before the aviator has time to manipulate the main switch of the ignition circuit; even when such switch is easily within his reach. Under such circumstances the engine may not only tear itself from its fastenings, but evenv go overboard before the aviator can fully realizewhat has consequences before the aviatorcan take come to pass; and when the fire due tothe escape of gasoline commences, it invariably/ because of the. high speed of the aeroplane,

trails backward. The flames can thus en- 'velop the aviator entirely and the end of both flier and flying machine may then be but a matter of a few seconds.

Such breakages are infrequent under ordinary conditions, but likely to happen, from gunfire. and accidentally, in war. When an aviator is in action he needs both hands and feet for his weaponsand controls. Y-Should a blade break or be shot off, he has small chance of saving;. for. even :if-he' recovers management, he necessarily sacrifices alti tude; which is I priceless; and determines whether he can pass the enemys barrage and get back into his own territory.

My invention aims to eliminate the danger of accidents such as I have justoutlined by mechanism which is quite simple, involving relatively few parts and comprising no construction which isbulky, complicated or expensive; and which can Joe-mounted upon an aeroplane or other airship so that it will instantly respondto an abnormal vibrationor other bodily movement of the engine driving the same, in order to' cutofi' the flow of ignition current to the spark plugs and cause the engine to stop developing power. way, in case a propeller blade should break, or something else should happen to unbalance the engine, the danger of the latter tearing itself loose an'dcau'sing a destructive fire is fully obviated. i O

Other objects and advantages of my invention will more clearly appear from the following description, taken in connection with the'accompanying drawings forming a part of the same; and the characteristics of my.

invention willbe precisely defined in the appended claim. This'disclosure, however,is explanatory only, and I reserve the right to adopt embodiments of my invention other than what is actually shown herein to the full extent indicated by thegeneral meanings of the terms in which the claim is expressed.

On the drawings Figure 1 is a diagrammatic view showing a complete power system for an airship, such as an aeroplane, for example; and the manner in which mechanism according to my v invention is utilized thereon;

Figure 2 is' a diagrammatic view of an aeroplane with engine and ropeller thereon,

showing mechanism accor ing'to my invention carried near the engine in front of the aviator, the observer viewing the parts men tioned from a point back of the engine;

Figure 3 is a' diagrammatic view of an aero lane en ine with its. propeller, showing urther t e manner in which my invention is mounted in relation to the engine;

Figure 4 is a plan view of a casing for enclosing mechanism used in the practice of m invention;

igure 5 is a plan view of the same casing showing the parts enclosed thereby, the cover being taken off Figure 6 is an inside view of .the cover of the casin showing the manner in which certain e ectrioal connections are made to the inside of the casing;

Figure 7 is, a section on the line 7-7 of Fi re 4; igure 8 is a section on the line 8-8 of .Fi re 4;

igure 9 is a central longitudinal section taken vertically through Figure 4; and

Figures 10 and 11 are diagrammatic views showing how my attachment can be modi-- The same numerals identify the same parts throu hout.

Refzrring to the first figure on the drawings, I show at 1 an internal combustion en gine supplied with ignition current through high-tension conductors 2, leading to the spark plugs of the engine from a magneto 3. This magneto may be of any approved design, with primary and secondary windings; and it is connected by a conductor 4 to a switch 5 which is joined by a conductor 6 to ground at 7. The switch 5 may be of the two-pole single-throw type, and is illustrated in open position; but when it is closed,

the primary armature winding will be shortcircuited around the circuit breaker or tlmer of the magneto in the usual way by the ground connection provided through "the conductors 4 and 6 and the operation of the ignition system will be suspended; so that the engine cannot continue running. My safety attachment for the engine is indicated as a whole at 8; and it is in multiple with the switch 5 through a conductor 9 connecting it to the conductor 4, and another conductor 1O joining it to the conductor 6. The arrangement of the parts of the attachment 8 is such that, as I shall set forth-fully hereinafter, the attachment 8 will-automatically cut off the ignition current by short-circuiting the magneto to the ground 7 and it is adapted to be operated by any abnormal bodily movement of the engine, as when there is an unbalanced condition resulting from a broken propeller blade. In that event the torque of the engine,"which would be normally divided by the blades and thus produce a balanced load, is then no longer properly divided; producin a badly unbalanced load, and pushing the engine from side to side as the propeller revolves. .Under such circumstances, a tractor plane is liable to go into a dive; a pusher plane into a tailstall; and, either is apt to pass next into a tail-spin, and the engine ma or may not go overboard entirely, this set pressure does become so great that engine is broken from its foundations and thrown out of the airship, the center of gravity of the machine is upset, completely destro mg its equilibrium, and effecting other an more serious damage. The attachment 8 produces a suspension of the operation ofthe ignition system to stop the'engine chiefly through the instrumentality of an element such as a pivotally mounted bar 11, comprised in the attachment 8, and housed in a casing 12. See Figure 5. This bar has sufficient mass, and it 1s supported upon its pivot 13 in the casing 12, so that it can move or swing or oscillate, like a pendulum, in a direction that extends across or transversely of the longitudinal axis of the engine 1; that is, the axis of the crankshaftv of same. Hence the bar should, preferably swing parallel to the plane of the propeller. The method of mounting referred to is illustrated in Figures 2 and 3. I may secure the attachment 8 to any part of the aeroplane so related to the engine that any transverse jar will instantly be transmitted to the bar 11.; hence I can mount the attachment either upon some part of the engine framework directly, or upon-a part of the aeroplane rigid with it ornear enough to'it to be subject to its vibration, such as the dashboard or instrument board will be the propeller 16; and at 17 is the outline of a part of the lifting planes or wings of the aeroplane. I secure to the back of the casing 12, a T-shaped fastening element having openings at the ends of the stem and arms, to enable the casing to be maintained 14. In front of the engine, on the shaft 15,

in the required position. As indicated in v tion transverse to the crankshaft, and the attachment can therefore perform its function when needed quite as easily as in the first instance, to respond to a transverse shock to the engine 1.

The casing 12 and parts borne thereby are illustrated in Figures 4 to 9 inclusive. It compri es a casting 19, forming the sides and ends; the upper end of the casting contractingsomewhat, soils to give approximate bar 11. As willappear presently, whenever the bar 11 is constrained by themotion of the engine 1 to swing sidewise into engagement with either element 23, the conductors 9 and 10 will be connected together, grounding the magneto, and stopping the engine 1 promptly. For the purpose of enabling the bar 11 to engage the contact elements 23 properly I secure to each side ofthe bar 11 a s ring contact element or'brush 24:, which will be pressed against the adjacent element 23 over virtually its whole length when the bar 11 is jolted or shaken to a suflicient. extent to make it perform its function.

Onthe outside of cover 21 ofcthe casing 12 are located twoelectrical .terminals or binding posts 25; one joined to the conductor 9 and the other to the conductor 10. The binding post 25 at the left in Figure 4: is secured to the overlapping ends of a pair of diverging strips 26 of electrically conductive material on the inner face of the cover 21; and theopposite end of each of these strips is made fast to a leaf spring contact element or brush 27. The shank or stem of the post 25 mentioned may have a nut on its inner or lower end to be screwed up tight against the two strips 26, as shown in Figure 6; and the elements 27' may be fastenedin place by screws extending from the outer face to the inner face of the cover 21, and throughthe strips 26; nuts being applied to the inner ends of these screws and turned up against spring brushes 27and strips 26. See Figure 6.

From the stem of the other binding post ex tends a single conductivestrip 26, on the inner face of the cover 21, to a central contact element 28,-on the outer face of the cover and, as illustrated in the two views last referred to, the contact 28 may have a threaded shank passing through the cover, and the inner end of this shank may receive a nut'to fasten the I shank and the single strip 26 together. The single strip 26 may be oined to the other binding post in the same way as the first joined to the two overlapping strips 26.

To cooperate with the contact 28 I utilize a switch 29, on the outer face of the cover 21; andv mounted on a metallic pivot or journal carrying on the inner face of the cover 21 a le'af-sprin ment 27; similar to t e elements 27 already mentioned. The switch 29 may beattached contact brush or eleto this pivot in'any convenient manner and the leaf springs 27 at the ends of the diverg- I I ing strips 26 connected to the post at the left 7 in Figure 4 will each rest on one of the contact elements 23; and the spring brush 27 under the pivot of the switch-29 will rest on the pivot 13. With the switch '29 engaging contact 28, obviously whenever the bar 11 is swung so as to move either brush 24; against the adjacentcontact'element 23, current will. flow from the. magne'to'3 through conductor 9, one of the diverging strips 26,

through the bar 11, switch 29," contact .28, and the binding post at the rightv to the conductor 10 and the framework of the -'en gine; and the further operation of the engine will thus be prevented.--

The elements 23, strips 126, brushes 27,

switch 29, and contact 28 :thereforeconsti tute conducting means or connections in the" casing attached'to the posts':.25; j'and these posts or; terminals are connected orbridged by means consisting chiefly ofthe bar11, un

der predetermined conditions, to en'sure the i 1 object soughtfafter; -Whenevera ground" connection is thus, established, upon the 00-- currence, of a seri'ous "accident "that might otherwise destroy the ,flying machinef and kill the flier, the: engine is stoppedinstantly; fire is-made impossible, and the aviator can volplane easily downtoterra' firms; without having to run the risk of further damage of o enable theaviator to make sure that the bar 11 is in central orneutral position under ordinary circumstances,; I make a transverse slot 30 in'the cover. '21,;and to the bar 11 I fix an index element orpointer 31 which projects through the slot: The middle .of this slot ismarked byxtwo lines 32, one" at each edge; When'the pointer '31':is between these lines, the bar 11 is away from both contact elements 23... When it is at either end of the slot, the aviator knows that the bar is'in engagement with one of these elements 23;

After the bar 11 is jolted. into engagement with one of theelements 23, ,in consequence of a mishap to the aeroplane, it is held against return to neutral position by suit and by each pair of lugs is supported a' catch 34. .Thelugs-of each element 23 carry apivot, pin 35, and this pivot. pin passes through the catch located between said lugs.

()n; the top of the lugs 33, moreover, the leaf spring 27, connected to the diverging strips- 'pression springs 42 one at each side.

26, connected to the binding post 25 at the left, will rest. Both catches 34 are preferably of insulation, but each will have a metal inset 36, which is formed to provide a shoulder or hook on the lower side ofits catch; presenting this shoulder or hook towards the lugs 33 supporting the catch. See Figures 7 and 8, On the upper face of the barll' is :1 lug or projection 37, and when the bar oscillates too much, this projection will slip under one of the catches till the shoulder or hook of the insert 36 therein engages it. The lower ends of the inserts 36 in front of the shoulders are bevelled; and so are the ends of the under faces of the catches. as Figures 7 and 8 indicate; so that when the bar 11 swings far enough, the projection 37 can slip easily under one or the other catch; this catch being free to lift slightly till the shoulder on its inset 36 snaps over the projection 37 and holds the bar against backward movement. Hence the short-circuiting of the magneto 3 is made permanent and certain.

To release the catches, the end of each be tween the pivot pin 33 thereof and the inside of the casing is engaged by appropriate means such as a plunger 38 in the ,cover 21. Each plunger has a stem extending through the cover and carrying adjacent the outer face of the same a head 39. Between this head and the cover is a spring 40. By pressing the heads 39, either catch can be operated to raise its end having the inset 36 to free the bar, and allow it to move back. Normally the ends of the catches under the plungers 38 are also engaged by compression springs 41 which act to cause the bevelled lower faces of the o posite ends of the catches to rest ightly on the bar 11.

Between the pivot 13 and the leaf-spring elements 24, the bar 11 is engaged by com- Each of these springs bears in a ocket 43 of a lug 44 on the bottom 20. Tie free end of the bar also carries a pin 45 which projects through a. slot in the adjacent part of the casting 19; and to this pm are secured two other springs 46, one at each side. Each pair of springs 42 and 46-constitutes means for damping the oscillations of the bar, and prevent it from engaging one of the contacts 23 under ordinary conditions. Each pair of springs also serves to restore the bar 11 to neutral position after one of the catches snaps over the projection 37, and is moved to release the bar 11. I also join the opposite ends of the sprin s 46 to eyelet bolts be 47, each of which has a end 48, movable in the bore of a.boss 49; The bosses 49 are at opposite sides of the casting 19, and the threaded outer ends of the bolts 47 carry nuts 50 and lock nuts 51. By manipulating the nuts 50 the bar 11 can be moved to exact central position, with the pointer 31 between the lines 32; and it will so remain when the lock nuts 51 are made tight, until occasion requires it to swing away from central position. The springs 46, with the bolts 47 and nuts thereon thus serve also as means for adjusting the bar 11 in addition to damping it, and by means of the bolts 47 and nuts 50, the tension of the springs 46 can be regulated as desired.

On the outer face of the cover 21 is a centrally located mark or indication just below the contact 28. When the switch 29, which controls the connections to be bridged by the bar 11, is in engagement with the contact 28, the indication 52 will be hidden and the operator will know that the attachment 8 is ready to act in case of emergency; but should this mark be visible, the operator will know that he must first close the switch 29, be fore he can rely on the attachment to do its work. The indication 52 may be made'by luminous paint, if desired, so as to be easily visible in the dark.

be manually moved into position to shortcircuit the magneto 3 for testing the instrument; and the switch 5 can be omitted entirely in the practice of my invention.

My attachment is of course not limited to gas engines, or aeroplanes, but may be used with other prime movers, and in other relations as well; if provided with electric circuits essential to regular operation.

My invention can also be ap lied to pusher planes as well as tractor p anes; and on dirigible balloons, because when a propeller on a balloon breaks fragments may puncture the gas bag and liberate the inflammable contents.

My invention is especially useful on military aeroplanes to promote the safety of the aviator against mishaps of the kind that are particularly met with in aerial warfare. In case of damage to a flying machine in a battle between two aviators in the clouds, such damage, if serious enough to threaten the destruction of the aeroplane, would very likely be accompanied by serious injury to the flier. Under such circumstances the aviator could not help himself, even if it were possible to manipulate the switch 5 in order to shut oil? the ignition current and sto the engine.

nder any circumstances, when an accident happens that causes the unbalancing of the engine, the time interval will generally be too short to enable the-switch 5 to closed; and even if the aviator could close the switch 5, if he has notbeen disabled, he would generally have enough to do in other directions, and furthermore, he might'not have the presence of mind enough to close the switch and save himself, es-

ecially if the accident were the first in his ymg experience. With the attachment 8 By means of the pin 45, the bar 11 can,

llh

Y causin the pendulum post and is automatically terceases so that fire canhow much gasoline is present the ignition minated and sparking not result no matter spilled.

The force of the springs on each side of the bar 11 is of course adjusted to make the attachment 8 inoperative within the limits of the safe operation of the engine; bar to remain neutral until that limit is exceeded.v

My attachment is equally well adapted for engines having ignition systems in which current is generated by means of a battery instead of a magneto; and, regardless of the fact whether a battery or a magneto is employed, I may connect it not only in parallel with the electrical generating device as shown in Figure l; but also in series, if desired. If the attachment is joined in this relation to the primary winding on the armature of a magneto, or to the primary of a coil connected at one end to a battery and at the other end to ground. the pendulum bar 11 must be arranged so that a shock will cause it to break the main circuit of the ignition generator, instead of merely connect it by a short circuit to ground. I can arrange the parts of my instrument without material alteration, in order to get this result, simply by dispensing with the spring brushes 24 and with the two spring brushes 27 and their strips 26 connected to the binding post 25, shown at the left in Figures 1 and 4. In place of these two strips 26 and these two brushes 27, I may employ a single strip 26, and a single brush 27 located near the middle of the wide end of the cover 21, in longitudinal alinement with the pivot post of the switch 29; and this single brush 27 will likewise be connected to the post 25 at the left; and will be arranged to rest directly upon the bar 11, say at a point near the catches 34. So long as the bar is in mid-position the current can flow from the generating device through the main circuit by way of this bar; but whenever the engine sustains a severe shock the bar will swing to the right or left, as before, and be engaged by one of the catches 34, thus breaking contact between the bar and the brush connected opening the circuit.

It sometlmes happens too that when an aviator is making a flight an accident may happen in some other manner than by the breaking of a propeller blade, and may cause a shock to the engine that is more or less parallel to the axis of the crankshaft instead of transverse to the same. Such a situation may result from a collision. If it is desired to guard against such a thing, the attachment 8 can be mounted so thatthe casing 12 will have its top 21 and bottom 20 parallel with the crankshaft of the engine, and with the bar extending either vertically or horito the left-hand binding zontall across the crankshaft of the same. With this arrangement a collision producing a substantially longitudinal shock will cause the bar to swing in a plane that is more or less parallel with the engine crankshaft, and suspend the operation of the ignition circuit with: the same result as in the first instance. In order to provide against mishaps from longitudinal shocks the attachment may be mounted so as either to short circuit the generator or directly break the main circuit of the same, as above described, whethera battery or a magneto is employed.

Furthermore, in order toguard against a mishap of both kinds; that is, anything that might produce a transverse shock to the engine or a longitudinal shock also; I may use two of my attachments 8 with the same engine, by mounting one so that the bar will be able to swing in a direction transverse to the crankshaft, as shown in Figures 2 and 3; and the other so that the bar can swing in a direction that is more or less parallel with the crankshaft. The two instruments may both be arranged, for example, so as to ground the magneto 3, whichever one takes eifect, by connecting the two instruments in parallel to each other; that is to say, simply by adding another instrument to the one shown in Figure 1, and connecting its left hand terminal to the conductor 9 and its right hand terminal to the conductor 10. Then in case of a collision, whichever of the two instruments allows its pendulum bar to swing in a direction parallel to the crank shaft will cause the short circuiting of the ignition system; and in case a shock occuring transversely of the engine, the other one will produce the required efiect. With the same effect I can also use the two attach ments 8 in series with each other, and with the generator, such as a magneto or battery; using in each attachment one centrally located brush 27 connected to the binding post 25 at the left, and arranged to rest on the bar 11; as already described; to break the ignition circuit instead of grounding it; but in any case'of this sort, the two instruments must likewise be arranged so that one will permit its pendulum bar to swing in a direction that extends longitudinally" of the engine; and the other must be supported so that its pendulum bar is free to swing. in a direction across that axis. With two attachments on an aeroplane, the ignition system can be interrupted in case of an accident that is caused by practically any shock to the aeroplane substantially parallel to the plane of the wings, whether longitudinal or transverse, or even in diagonal directions; although the mode of operation will be best and surest of course when the shock is either directly transverse or directly along the length of the engine.

In Figures 10 and. 11 I show diagrammatically a combination of parts which in-' wings or lifting planes 17. Instead of two contact elements 23 Iutilize a conductor ring b 53 with which cooperates a pendulum conducting bar 54 that is suspended at the middle of the ring and can swing when released towards any point in the circumference of the ring. The lower end of this bar is rounded and it engages a head 55 having a shallow recess 56 which the end of the bar enters. The head 55 is carried on the upper end of a stem 57 which is encircled by a helical spring b 58 and normally tends to press the bar 57 toward the ring. So long as the bar 54 and stem 57 are in alinement, the bar 54 will be kept away from the ring, but in case of a. shock coming from any stantially parallel to the plane of the ring or even at some angle with this plane, the bar 54 will be shaken free from its engagement with the head 55 and impelled over towards the ring 53 until it is stopped by the latter. When this happens of course the spring 58 impels the head 55 upward, and this head will be surrounded by a suitable insulating collar 59 which 'will slip behind the lower end of the bar and hold it against the ring 53 until the stem 57 is withdrawn to release the bar 54 and let it swing back to original position.

the upper end of This stem 57 may be mounted to reciprocate in a bearing 60 against which one end of the spring 58 abuts, the other end abutting agamst the lower face of the collar 59; the upper face of this collar being rounded off or made approximately spherical.

At its up er end the ar 54 is likewise rounded, an abuts against a hearing member 61 having a rounded recess 62 which permits the end of the bar to move therein. Through the top of the bearing member 62 extends a short tubular section 63, and from the bar 54, through this section extends a flexible suspension element 64, such as a length of light chain or iece of wire, which passes through the section 64 and secures the bar 54 in contact with In other words, the suspension element 64 simply passes through a hole in the bar 54 up through the section 63 and may be hung at the top of the section 63, so as to draw the bar 54 against the lower end of the tubular element 63 and bearing member 61. This element thus suspends the bar and it will be connected to the ground wire 10 while the ring 53 will be the member 61.

' 10ined to the wire 9.

direction that is subworking against lating or dispensing with When a shocktakes place then the bar will swing over against the ring as shown in Figure 10, and the head 59 will serve the same purpose as the catches 34 above described. The bearing 60 will be slotted as at 65 and through this slot will extend an arm 66 connected to the stem 57 to enable the operator to pull down the stem 57 when he desires to release the bar able means may be employed caring 60 and spring 58.

The part shown in Figures 10 and 11 may be mounted in a suitable casing which will be fixed to the aeroplane in such a man- 54. Any suitregulate the force of the nor as to respond to a shock to the engine,

but must preferably be so arran ed that the bar 54 will always be substantia ly vertical. After a shock produces contact between the ar 54 and ring 53 the operator has only to pull down the stem 57 far enough to let the bar swing back and then let the stem go up again to cause the lower rounded end of the bar to enter the recess 56. Preferably the collar and the head 55 are flattened around this recess so as to provide a sufficient surface to engage the bar and steady it if, on the first attempt, the operator is not successful in bringing the end of this bar and the recess 56 together. In such a case only two or three other attempts will be required before the bar will on its suspension element 64, to enable the stem 57 to move the head 55 with the recess 56 directly a ainst the lower rounded end of the bar. f course I may also provide a casing with buttons on the outside spring-plungers, like the plungers 38 above mentioned; and by pressing these plungers in with his fingers, the operator can steady the bar 54, after depressing the stem 57 sufficiently, to bring about reengagement of this bar and the head 55 after the effects of an accident have been disposed of.

The combination shown in, Figures 10 and 11 is illustrated as being adapted to short circuit the ignition system. It may also be utilized to break the main circuit of the ignition system directly, simply by connecting the wire 9 to the bearing 60 and insuthe'ring 53. Curthrough the stem will throw these rent will then flow directl 57 and bar 54 and a shoe two parts out of engagement and thus interrupt the flow of current.

Obviously the combination shown in Figures 10 and 11 will operate just as well if the bar 54 and stem 57 are held in horizontal position. If these two arts extend longitudinally of the engine they will respond to a transverse shock to interrupt the ignition supported in horiextending across the axis of they will respond to the shock system; and if they are zontal position, the engine,

to adjust the hang perfectly motionless l 11 may have damping 5 rings like those shown at 42, for examp e, four at right angles to each other, connected to the bar 54; and the collar 59 serves as retaining means when it is pushed toward the ring 58 to hold the bar and ring in contact. This type of attachment constitutes means com-' prising an element that can be moved either in a direction transverse of the longitudinal axis of the engine or in substantially the same direction as the axis to suspend the operation of the ignition system and sto tion of the instrument being changed; once it is supported so that the bar 5 1: and stem 57 are vertical; while, as ointed out above,

in order to make the attac ment 8 in Figure 1 operate in case of a longitudinal shock, the position of it must be changed so that the bar 11 can swing in the direction of the crankshaft 15.

Having described my-invention, what I claim to be new, and desire to secure and protect by Letters Patent of the United States is as follows:

Mechanism for stopping aninternal combustion engine comprising a pivotally suspended bar, a contact element on each side of said bar, means for damping the oscillations of said bar, and means for adjusting said bar to neutral position between said elements.

In testimony whereof, I have signed my name to this specification this 4th day of the engine from rotating, without the pos1-'- December, 1917.

THEODORE DOUGLAS. 

